What are the sub-phylum of prochordates?

The sub-phylum of prochordates are:

i. Hemichordata – Marine organism without backbone.

Balanglossus (Hemichordate)

ii. Cephalochordata – Small fish with unpaired dorsal fin.

iii. Urochordata – The adults are mostly degenerate, and are sessile forms.

Ascidian (Urochordate)